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Agenda
VDO Fundamental
Properties of VDO Digital
VDO Formats
Digital VDO Production
Record
CaptureEdit
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Properties of VDO
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Analog VDO
• Motion VDO was originally created and stored in analog form.
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Digital VDO
• A means of reproducing the continuous VDO waveform as a stream of digital numbers.
Benefit: immune to various
distortion attributed to analog
such as noise...
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Interlacing• Interlacing was originally conceived as a way
to achieve good visual quality within a limitations of a narrow bandwidth.
odd field even field
open wiki to embrace the explanation!!
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Progressive Scanning(non-interlaced scanning)
• A method of representing moving images on a display screen, in which every pixel is represented in each frame.
• Computer monitors use a progressive scan.
• The standard refresh rate for a flicker-free display is a vertical scan rate of 75 Hz or higher.
• It’s used to project movies in theaters.
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Notein digital TV terminology:
interlaced scan is denoted by a lowercase i
progressive scan is denoted by a lowercase p
frame rate: (60i, 24p)resolution: (1080i, 720p)
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Flicker Rate
• Flicker fusion rate is the human eye’s ability to notice flicker within rapid pulses of light.
• Flicker will be observed if a light pulses on and off below 72 pulses per second (pps).
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Frame Rate
• Frame frequency is a measure of how quickly an image device can produce unique consecutive images called frames. (expressed in frames per second - fps)
• Typically, the human eye can interpret motion at 10 fps, but this rate causes a flicker effect that’s distract.
• Increasing the frame rate reduces flickering.
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Frame Rate
• Movies - 14 fps
• Television:
• NTSC - 29.97 fps
• HDTV - 60 fps
• VDO games (frame rate is very important):
• action-oriented games - 20-30 fps
• 3D-heavy games - 90-100 fps
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Aspect Ratios
• The ratio of the width of the image to its height (w:h)
• motion-picture - 1.85:1 and 2.35:1
• tv screens - 1.33:1 (aka 4:3)
• HDTV - 1.78:1 (aka 16:9)
16:9 4:3 letterbox
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Compression• VDO is huge - one sec of analog VDO
stored in an uncompressed digital format takes up 1 MB of disk space
• thus, 5-min VDO ~ 300 MB
• not practical
• VDO compression is a MUST
• VDO contains many spatial and temporal redundancies
• Codecs are needed for creating and viewing
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Digital VDO Formats
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AVI
• Most common AV data on Windows
• Can be saved in a variety of compression schemes - full frames (uncompressed), Radius’s Cinepak, Intel Video, and Indeo.
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MOV
• Quicktime Movie was developed by Apple Computer
• MPEG-4
• Qt 7 use H.264
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MPG
• The compressed VDO file format for standard DVD using the MPEG-2 encoding standard
• A large file can be transferred to MPEG with little loss of quality while dropping the bit rate a great deal
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• The MPEG group develops the standards for encoding VDO and audio
• MPEG standards:
• MPEG-1: used as VCD standard (MP3 is the popular compression)
• MPEG-2: use in many things such as DVD, digital satellite TV and so on
• MPEG-4: support 3D content, low bit-rate encoding, support for Digital Right Management
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• WMV
• a part of Windows Media framework
• used for streaming VDO over the internet
• uses MPEG-4 standard
• RM
• a multimedia container with RealVideo and RealAudio codecs in a single file
• is used to stream AV over the internet
Others
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VDO Production
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Equipments
• Digital tapeless (D)
• HDV (D)
• DV (formerly DVC)
• 8mm (A)
• VHS (A)
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Connecting Recorder to Computer
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Coaxial
• VDO and audio signals are both carries in one cable
• Poorest transfer
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A/V• Use RCA connectors
• Yellow is (composite) video
• Red is right audio & White is left audio
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S-Video
• Separate video - transmit VDO signals over a cable by dividing the VDO info into 2 separate signals: color (chrominance) and brightness (luminance)
• Sharper than composite VDO
• must be used in conjunction with audio cables
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USB
• USB 2.0 are common
• 480 Mbps
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FireWire
• Developed by Apple Computer
• IEEE-1394 standard
• 400 Mbps
• higher transfer rates are available (800, 1600, and up to 3100 Mbps)
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Transferring from Recorder to Computer• Calculate disk space (uncompressed):
• (pixel width) x (pixel height) x (color bit depth) x (fps) x (duration in secs) / 8,000,000
• say, 3-min VDO @ 15 fps, 24-bit depth, 320x240 pixels will take:
• (320) x (240) x (24) x (15) x (180) / 8,000,000 = 622 MB
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VDO Editing
• Editing:
• cut and paste sections
• add special effects
• add transitions
• add titles
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